Elon Musk approached Meta CEO Mark Zuckerberg earlier this year, asking him to help finance xAI’s bid to buy Sam Altman’s OpenAI, according to a court filing released Thursday. The call for help came after a long history of tension between the tech superstars.

After founding OpenAI with Altman in 2015, Musk has taken issue with OpenAI’s closed-source model and its push to become a for-profit entity. Thursday’s filing is part of an ongoing lawsuit Musk filed against OpenAI in federal court in Northern California in August 2024, alleging OpenAI breached its initial contract by favoring business interests over its initial commitment to benefiting humanity. 

Musk doubled down on efforts that were interpreted as preventing OpenAI from rapid growth, making an unsolicited attempt to buy the company for $97.4 billion in February. Beyond the OpenAI board unanimously rejecting the offer, OpenAI called the effort a “sham bid” designed to impede the company’s funding efforts.

Earlier this month, a judge allowed OpenAI to move forward with counterclaims against Musk. On Thursday as part of the claims, OpenAI said in a statement to the court that Musk had approached Zuckerberg regarding a letter of intent “about potentially financial arrangements or investors” in a bid for a hostile takeover of OpenAI. Neither Meta nor Zuckerberg signed the letter of intent, according to the filing.

The filing also subpoenaed Meta to disclose documentation of correspondence with Musk or xAI regarding an intent to buy the startup.

Beyond feeling as though OpenAI had strayed from the mission he helped create for it, Musk had other reasons to want to best the company. He left the startup’s board in 2018, the year before Microsoft pumped $1 billion into the company. Months after Microsoft announced another $10 billion investment in OpenAI in 2023, Musk unveiled xAI as an alternative to ChatGPT.

“I don’t disagree necessarily with his viewpoint that the restructuring of OpenAI as a for profit company is probably not good for humanity,” Amelia Martella, adjunct professor and executive director of Fordham University’s Corporate Law Center, told Fortune. “At the same time, he is probably looking to control all of the successful AI companies. So there’s a mixed motive for sure.”

Meta’s next moves

Meta, on the other hand, has carried out its own campaign to gain an edge over OpenAI, restructuring its AI division with a focus on building a superintelligence team and poaching key AI architects, including former OpenAI employees. According to Altman, Meta offered $100 million signing bonuses to recruit talent from its rival.

Musk’s own apparent approach to Zuckerberg in his bid for OpenAI defies nearly a decade of hostility between the two tech founders, beginning in 2016 when a SpaceX rocket explosion destroyed a Facebook satellite on board. The beef continued through last year, when Musk challenged Zuckerberg to a cage match.

Meta objected to the request for documents as “overly burdensome,” according to the filing. 

“Meta’s documents can hold no evidence of ‘coordination’ with Musk, or of Meta’s purported attempt to purchase OpenAI, or of any other relevant information when Meta did not join Musk’s bid,” Meta’s statement in the court filing said. “Meta’s communications (if any) with entities that did join the bid also hold little to no relevance, and in any event, should be sought from those entities, not Meta, which did not participate.”

Meta and Musk’s attorney Marc Toberoff did not respond to Fortune’s request for comment.

Meta will likely try to narrow the scope of the subpoena because it takes effort and time to turn over documentation, and because the company may feel OpenAI’s grievances should remain with Musk, Martella said.

“Musk is leading the charge here. That’s not surprising,” she said. “We don’t know what [Meta’s] role is here and how far along in the process they’ve gotten, so they may just not want to bother fully responding to subpoenas when they have not really been the one leading the charge.”